Bandgap reference circuit

DETAILED DESCRIPTION In accordance with the present invention, a self-starting bandgap reference circuit is provided.
"Self-starting" is related to two main factors: an op amp with a negative offset regardless of conditions of an application and a stable bias current generated by an input voltage.
One embodiment of the bandgap (BG) reference circuit provides start-up requirements at substantially any voltage and at substantially any temperature.
In a simple BG configuration comprising a balanced op amp (e.
g.
, two stages of transistors) and a network of resistors and bipolar diodes, the well-balanced op amp output remains in low mode since its offset is about +1 mV by design (systematic offset).
With a low output, the op amp is not able to supply the network of resistors and diodes, and thus the bandgap reference circuit remains inert.
If an artificial offset of about -5 mV is introduced to the [+] branch/terminal of the op amp, then the op amp output will be high as soon as the power supply exceeds the transistors' threshold levels.
The op amp output supplies the resistors and diodes network and brings the op amp inputs within desired regulation voltages.
One embodiment of the invention relates to a practical, relatively simple bandgap (BG) reference circuit with complementary metal oxide semiconductor (CMOS) transistors or bipolar transistors.
The BG reference circuit advantageously provides moderate accuracy and low power consumption in a wide range of temperatures and input voltages.
The BG reference circuit provides better stability and a low cost production yield.
In one configuration, the BG reference circuit specifications include a maximum +/-6 mV voltage change in a temperature range of -40.
degree.
C.
to +125.
degree.
C.
and between about 2-V to 8-V power supply.
This means that the bandgap voltage (BG)=1.
240V +/-6 mV.
The bandgap reference circuits and methods described herein may be implemented in several products or applications without any adverse effects.
One advantage of the circuits and methods is their relative simplicity